1. Field of the Invention
This invention relates to a new process for marking currency with a nuclear signature to permit easy and positive authentication at a later date. More particularly, the invention relates to a new process for marking currency with a nuclear signature which uses equipment not available to the public and thus impossible to duplicate or counterfeit.
(As used herein "signature" and "marking" refers to the incorporation of a permanent mark on currency which can later be indentified and authenticated.)
Specifically, the invention provides a new process for marking currency to permit easy and positive later authentication which uses advanced nuclear reactor or linear accelerators, which are not available to the public and securely protected. The new process broadly comprises exposing a small region of the currency to bombardment by high energy neutrons for a short period to effect a high state of excitation in the atoms of the exposed region, and then treating the exposed small region with a chemical reagent which reacts with the excited atoms and leaves tiny holes in the said exposed region which can later by identified.
The invention further provides a special embodiment wherein separate material, such as mylar tape, is treated as in the above process and then incorporated into the preparation of the currency so the finished currency will still contain the desired markings.
The invention further provides a process for authentication of the currency which has been marked as above which process comprises exposing the marked currency to monochromatic X-ray source, allowing the transmitted beam to impinge upon a fluorescent screen which will show shiny dots where the beam has reached the screen, said dots corresponding to the tiny holes in the marked currency. Conventional optical detection (photographic) and computer interfacing will permit rapid evaluation and compliation of data.
2. Prior Art
The fabrication and circulation of counterfeit United States currency has grown into a major problem. The yearly increase in counterfeit currency is estimated to be between 8% and 16%. According to the Wall Street Journal, about $87 million in counterfeit was confiscated during 1984 alone. Presence of large amounts of counterfeit money has many undesirable effects on the society as well as on the economy.
While techniques do exist to distinquish between authentic and counterfeit bills, these methods are generally time consuming, expensive, and cumbersome. In addition, since sophisticated techniques of counterfeiting are presumably in criminal hands, the services of an expert is required to distinquish the real from the counterfeit currency.
What then is needed is a rapid, inexpensive and simple technique of detection which can distinquish between authentic and counterfeit currency and which can be operated by less skilled employees.
It is an object of the invention therefore to provide a new process for marking currency for easy and positive later authentication. It is a further object to provide a process for marking currency for later identification which is rapid, inexpensive and easy to operate. It is a further object to provide a process for marking currency for later identification which uses equipment not available to the public and impossible to duplicate by counterfeiters. It is a further object to provide a process for marking currency which imparts a marking in a very small area and which is impossible to detect other than with the required equipment. It is a further object to provide a process for marking currency which permits rapid and positive authentification by the use of equipment that will readily be available to all banks and other institutions. It is a further object to provide a method for marking currency for later authentification which provides a detection system which can be operated by even those of limited skills. These and other objects will be apparent from the following detailed description thereof.